1. CLINICAL INVESTIGATION UNIT TESTS
Presented by:
ALAA MONJED
Endocrinology fellow

2. OUTLINE CIU tests Indications Side effects / Contraindications
Background- Provocative endocrine tests
CIU tests
Indications
Side effects / Contraindications

3. Background basal hormone levels
What can we measure?
basal hormone levels
stimulated or suppressed hormone levels
Why do we do dynamic endocrine testing?
test of secretory reserve

4. INSUFFICIENCY/DEFICIENCY
Stimulate!
OVERPRODUCTION
Suppress!

5. Clinical Investigation Unit - CIU
Liz Froats, RN
Room B5-502

7. Pituitary Hormonal Disorders
Available CIU Tests
Pituitary Hormonal Disorders
Tests
Acromegaly
Oral Glucose Tolerance test
GH deficiency
Insulin Tolerance test
Arginine/GHRH Stimulation test
Glucagon Stimulation test
Adrenal insufficiency
ACTH Stimulation test
CRH Stimulation test
Central hypothyroidism
TRH Stimulation test
Hypogonadotropic Hypogonadism
GnRH Stimulation test
Anterior Pituitary insufficiency
(Double or Triple Bolus test)
Diabetes Insipidus
Water Deprivation test

8. Non-Pituitary Diseases
Tests
Medullary Thyroid Cancer/Calcitonin
Calcium Stimulation test
Pentagastrin test
Hyperaldosteronism
Saline Infusion test
Pheochromocytoma
Plasma Catecholamines test
Hypoglycemia
8+ hour Fast test
Mixed Meal test

9. Examples

10. EVALUATION OF GROWTH HORMONE DEFICIENCY
Screening test: low IGF-1 level
but normal IGF-1 does not exclude it
Dynamic tests:
because basal levels of GH are usually low, which do not distinguish between normal and GH- deficient patients.
Insulin induced hypoglycemia
Most reliable stimulus to GH secretion
A subnormal increase in serumGH (<5.1 ng/mL) confirms the diagnosis of growth hormone deficiency
the presence of deficiencies in > 3 pituitary axes strongly suggests GH deficiency, and in this context, provocative testing is optional
adults with structural hypothalamic/pituitary disease, surgery or irradiation to these areas, or other pituitary hormone deficiencies should be considered for evaluation for acquired GH deficiency (level of evidence – high)

12. ITT 14 units of insulin given
Time
Glucose (mmol/l)
GH (ug/L)
3.96
1.77 15
1.2
0.98 30
0.8
3.24 60
2.3
3.26 90
1.3
2.83
120
2.1
0.95

13. Interpretation: Why? abnormal Glucose fell to <2.2 mm
Normally GH should rise over 10

14. 2. GHRH-Arginine test
1mg GHRH combined with a 30-min infusion of Arginine IV to stimulate GH secretion
Possible side effects: mild flushing, metallic taste, N/V
Contraindications: severe liver or renal disease

15. 3. Glucagon stimulation test
1 mg Glucagon IM, followed by measurement of GH every 30 min for 3 hours
Useful when ITT is contraindicated or GHRH is not available
Side effects: nausea, vomiting and possible late hypoglycemia
Contraindications: malnourished patients
Failure of GH to rise > 3ng/ml is a positive test

17. Evaluation Of GH Hypersecretion/Acromegaly
Screening test: high IGF-1 level
Dynamic tests:
Oral glucose tolerance test
Failure of GH suppression or paradoxical rise in GH level confirms Acromegaly
Also, seen in starvation, anorexia nervosa, and protein- calorie malnutrition
Side effects: nausea
If a radioimmunoassay method= GH level > 1mcg/L
If one of the newer, highly sensitive immunoradiometric GH assays is used= GH level > 0.3 mcg/L

19. Interpretation? Time GLUCOSE (MM) GH (ug/L) 0 min 4.7 19.7 30 min 11.015
60 min
7.5 12
90 min
5.3
10.8
120 min
3.1
14.9
Interpretation?

20. Evaluation Of LH/FSH Deficiency
Measurement of gonadal steroids (estradiol, testosterone).
Measurement of LH/FSH.
Primary gonadal failure
Low gonadal steroids, High LH/FSH
Hypogonadotrophic hypogonadism
Low gonadal steroids, LH,FSH
GnRH test
Assess LH/FSH secretory reserve by stimulating their secretion
Uncommonly performed

22. Evaluation Of TSH(Secondary Hypothyroidism)
Measurement of TSH
Measurement of free T4/free T3
If high TSH, low T4 …….
If low/normal TSH, low T4 …….
3. TRH stimulation test
is rarely done now because of the accurate methods of determining TSH and freeT4

24. EVALUATION OF HYPOPITUITARISM
Components:
Insulin Tolerance Test
GH deficiency, adrenal insufficiency
GnRH stimulation test
hypogonadotropic hypogonadism
TRH stimulation test
central hypothyroidism, hypoprolactinemia

25. 1984. J Neurosurg 61(3):

26. ACTH and Cortisol Secretion
Kronenberg HM et al. Williams Textbook of Endocrinology. 11th edition Saunders Elsevier.

27. ACTH and Cortisol Secretion
pulsatile secretion
circadian rhythm
highest in a.m.
24:00
08:00
12:00
20:00
Kronenberg HM et al. Williams Textbook of Endocrinology. 11th edition Saunders Elsevier.

28. Pituitary-Adrenal Reserve Dynamic Tests
Used to evaluate the ability of the HPA axis to respond to stress
ACTH stimulation test: directly stimulates adrenal secretion
Metyrapone test: inhibits cortisol synthesis and stimulates pituitary ACTH secretion
Insulin-induced hypoglycemia: stimulates ACTH secretion by increasing CRH
CRH test: stimulates directly the pituitary corticotrophs to release ACTH

29. Adrenal Insufficiency Diagnosis
Steps:
To rule out adrenal insufficiency - fasting 08:00 am cortisol
if 08:00 am cortisol >524 nmol/L, adrenal insufficiency excluded
if 08:00 am cortisol <83 nmol/L, adrenal insufficiency confirmed
if 08:00 am cortisol between these values, is borderline – need further testing
reviewed in Oelkers W. N Engl J Med 1996; 335(16):

30. Adrenal Insufficiency Diagnosis
Steps:
If suspect primary adrenal insufficiency, do both 08:00 am cortisol and ACTH
low cortisol and high ACTH - primary
if cortisol normal – rules out primary, but does not exclude mild secondary adrenal insufficiency
in primary adrenal insufficiency – ACTH usually >22pmol/L
low cortisol and low/normal ACTH – secondary/tertiary
.11pmol/l

31. Adrenal Insufficiency Diagnosis
Dynamic Tests:
To confirm adrenal insufficiency:
High dose ACTH stimulation test
Fasting is not required
250 mg cosyntropin (Cortrosyn) IV/IM
Cortisol/ACTH at -15, 0, 30, 60 min
If peak cortisol >500 nmol/L (preferably >550 nmol/L), rules out primary adrenal insufficiency
Oelkers W. N Engl J Med 1996; 335(16):

33. A normal response to ACTH stimulation test:
Excludes primary AI
Excludes overt secondary AI with adrenal atrophy
Dose not rule out partial ACTH deficiency
pts with sufficient basal ACTH secretion to prevent adrenocortical atrophy
Or pts with recently developed secondary AI who have not yet undergone adrenal atrophy
In such patients, other pituitary-adrenal reserve dynamic testing may be indicated
because of high dose (only need 5 mg to maximally stimulate adrenals), and if recent – adrenals will not have atrophied yet

34. Adrenal Insufficiency Diagnosis
Low dose short ACTH stimulation test
must be undertaken in the morning
1 mg cosyntropin (Cortrosyn) IV
Cortisol/ACTH at -15, 0, 30, 60 min
Normal peak cortisol >500 nmol/L
2 meta-analyses comparing low vs. high dose tests had conflicting results:
Dorin et al – no difference in sensitivity or specificity
Kazlauskaite et al – low dose test had higher sensitivity
Oelkers W. N Engl J Med 1996; 335(16):

35. Adrenal Insufficiency Diagnosis
Insulin-induced hypoglycemia test:
It measures the integrity of the HPA axis and its ability to respond to stress
Normal plasma cortisol response: an increment >220nmol/l and a peak level >550 nmol/l
Normal ACTH response > 22pmol/l
A normal response exclude AI and decreased pituitary reserve i.e. no need to cortisol therapy during illness or stress
Contraindicated in: Elderly, CVD, CVA and seizure disorders

37. Adrenal Insufficiency Diagnosis
To distinguish secondary vs. tertiary adrenal insufficiency: CRH stimulation test (if you can get CRH!)
100 mg CRH IV
ACTH, cortisol at -15, 0, 30, 60, 90 min
low/absent ACTH = pituitary adrenal insufficiency (secondary)
high ACTH = hypothalamic adrenal insufficiency (tertiary)
(values not as well standardized as for ITT)
Oelkers W. N Engl J Med 1996; 335(16):

38. Posterior Pituitary

39. Diabetes Insipidus Central Antidiuretic hormone deficiency
Responds to Desmopressin
Diagnosis:
Water Restriction Test

41. Water Restriction Test

42. Water Deprivation Test
TIme
Weight (kg)
Urine osmol
Serum osmol
Serum Na
0800
82.6
150
290
144
0900
82.4
160
1000
82.1
200
295
148
1100
81.9
210
1200
81.6
225
300
149
1300
81.5
211
312
1400
81.1
231
1500 **
487
298
145

43. Interpretation: abnormal, consistent with central DI
Why?
Serum osmolality rose but urine osmolality remained relatively dilute still; similarly serum Na rose
[At ** time DDAVP was given and serum/urine/Na responded appropriately]

44. REFRENCES
Kronenberg HM et al. Williams Textbook of Endocrinology. 11th edition Saunders Elsevier.
Gardner DG & Shoback D (eds) Greenspan’s Basic & Clinical Endocrinology, 9th Edition McGraw-Hill. m

45. THANK YOU